Electrical wire connector



March 3, 1942. G. c. THOMAS, JR

ELECTRICAL WIRE CONNECTOR Filed Aug. 29, 1940 FIG. 2.

ATT RNEY Patented Mar. 3, 1942 ELECTRICAL WIRE CONNECTOR George c.Thomas, Jr., Elizabeth, N. 1., minor to The Thomas); Betta (10.,Elizabeth, N. 1., a corporation of New Jersey Application August 29,1940, Serial No. 354,668

I 3 Claims.

This invention relates to solderless connecting means for joining theends of one or more electrical conductors or for installing saidconductors or wires in service position, and more particularlyappertains to an electrical wire connector.

In general, the solderless electrical-wire connectors now largely in usecomprise a plurality of assembled parts which present a number of jointsor connections resulting in cumulative resistance to current flow, andit is an object of this invention to produce a solderless electricalwireconnector or terminal which not only has a minimum number of parts inits assembly by reason of my new construction but mor particularlyemploys only on part in the current path, together with otheradvantages.

A further object is to produce a connector which is self contained, thatis, a minimum number of two parts are permanently joined duringmanufacture of the connector and do not require assembly by the wiringmechanic on the job, and which has a minimum outside diameter for agiven maximum-size internal passage to receive a maximum-size electricalconductor thereinto.

With the foregoing and other objects in view, the invention relates tothe new construction and combination of parts as shown in theaccompanying drawing, wherein:

Figure 1 shows an eyelet-face view and an edgewise view of. the internalcontact part blanked flat from sheet metal.

Figure 2 shows the part in final form with its electrical contact endpressed into a troughshaped contact tongue.

Figure 3 is a perspective view of a tubular reinforcing outer shell intowhich the contact tongue of the other part is pressed and held as anassembled fit.

Figure 4 shows an eyelet-face view and an edgewise view of the completedconnector, the eyelet-face view being broken and in section as along theline 4-4 of Figure 6.

Figure 5 also shows an eyelet-face view and an edgewise view of theconnectorjoined with a stranded-wire electrical conductor.

Figure 6 is an enlarged cross section taken on the line 6-6.

Figure 7 is a cross section on the line 1-! showing the wire strands inthe connector with a crimping depression applied through the double-wallside of the connector.

Figure 8 also is a crosssection like Figure 7, except the crimpingdepression is applied to the single-wall side of the connector.

Referring further to the drawing, a current transmitting part,preferably of soft copper, is punched from sheet material and has anelectrical contact or wire engaging end portion 2 with an integral neck3 and an eyelet end 4. The contact end 2 has its inside surface serratedor perforated or otherwise roughened in a known manner to establish aneffective bonding and gripping connection with an electrical wireconductor. For small wire, thin soft sheet stock copper or othermaterial is used to make this part, while for larger wire a thickergauge sheet metal may be used.

The contact end 2 is pressed or stamped into final form (Figure 2) oftrough-shape or. substantially semi-circular in cross section. In fact,the contact tongue 2 is preferably made initially sufliciently wide asto deform it into final shape with an arcuate body in cross section of alittle more than This makes thesides of the trough-shape contact portion2 define an arc of slightly more than a half circle.

In addition to the foregoing, the two longitudinal edges of the arcuateportion 2 are preferably reduced in thickness from the center or bottomof the trough outwardly so as to featheredge down to thin form. This isaccomplished when drawing or reducing the portion 2, by a stamping ordie-pressing operation, which produces a trough-shaped part of graduallyreduced thickness from the bottom thereof outwardly to its upper thinedges 5, thereby forming a crescent shape portion in cross section witha thick center and thin edges.

The semi-circular contact portion 2, and likewise its crescent-shapeform as shown, is'a feature making for a minimum outside diameterconnector with a maximum inside diameter passage adapted to receive amaximum size wire W. The wire W rests within the connector somewhatoiI-center of an outer shell 1, that is, the wire rests between theinner surface of the crescent contact portion 2 and inner surface of theshell I.

The trough-shape or crescent contact portion 2 occupies a minimum ofspace within the shell 1, thus receiving a maximum size wire intotheconnector. Reduction in overall size of the connector is the result, andit follows that the outside diameter of the insulation on the wire Wmore nearly equals the outside diameter of the shell, thus making for aneat wiring assembly.

The length of the tubular or cylindrical reinforcing sleeve or shell 1is about equal to that of the contact portion 2. This shell 1 may beformed of hard metal, say of hard drawn bronze or copper tubing whichhas high tensile strength and hence offers substantial resistanceagainst deforming from its crimped shape, as later explained. The insidediameter of the outer shell is substantially the same as the outsidediameter defining the arcuate inner contact tongue 2.

The reinforcing bronze or hard copper shell.

nector assembly.

Since the arcuate contact 2 is more than 180 in cross-section it isforced to a firmly fitted seat within the shell I. In other words, thelongitudinal edges 5 reach beyond the diametrical center or more thanhalf-way around the inside of the shell which is an arrangementsimulating the interfitting coaction between two complete cylinders, butdoing so without actually making the inside part in full-cylindricalform. The reach of slightly more than 180 causes the inner halfroundportion 2 to hug its seat against the inside of the shell I and form aconnector of doublewall thickness on one side and single wall on theother side.

In the use of this connector, a wire W, if covered by insulation, hasits end trimmed clean of said insulation and introduced into the tubularshell I in engagement with the serrated surface of the soft metal tongue2, with the shoulder of the cut insulation abutting the end of theconnector. Crimping pressure is now applied, as indicated at C pointingto a lengthwise groove or depression forced into the connector. Acrimping or pressing tool of any suitable form is used for this purpose.

Preferably, the compressed groove C is applied longitudinally of theconnector, hence parallel with the wire W therein, and extendssubstantially from end to end of the shell I. By enforcing the crimpingdepression longitudinally in the connector there is produced alengthwise gripping of the entire area of the soft metal contact tongue2 against the wire which affords the maximum area of pressure electricalbonding engagement. It also follows that the thin edges 5 of the contactpart act to gather in the wire strands and crowd them into alongitudinally packed cold-flow mass which forms a permanent andeffective electrical joint or connection.

The soft metal tongue 2 deforms and squeezes by cold-flow grippingengagement into the strands of the wire W. In fact, the serrated orotherwise roughened surface of the soft copper portion 2 finds its wayby pressure into the interstices of the wire strands and establishes apositive electrical cold-flow pressure connection therewith. Thisfunction also results when applying the ccnnector to a single wireconductor, except that the gripping pressure exists externally about thecylindrical surface of the single wire.

' The internal compression applied to the wire W by the gripping forceof the crimping groove C is maintained permanently, whether crimpedthrough the double-thickness wall (Figure 7) or through the single-wallthickness (Figure 8); it is satisfactory to apply the crimp C anywherearound the connector. The outer shell takes a permanent-set crimp C andmay be made of copper or preferably of hard drawn material or hightensile bronze tubing. Thus, the crimping groove C forced into theinterfitted parts 2 and I produce an unusually efficient electricalconnection with the electrical wire W because the reinforcing shellmaintains the internal cold-flow compression of the parts, and the outershell 1 like Wise grips and engagesthe wire. This connector is ofminimum size for maximum size wire and makes an effective and neatwiring job.

This invention is presented to fill a need for a useful electrical wireconnector. It is understood that various modifications in construction,operation, use and method, may and often do occur to those skilled inthe art, especially after benefiting from the teachings of an invention,and that this disclosure is exemplary of the principles but not limitedto the present embodiment of the invention.

What is claimed is:

l. A solderless electrical-wire connector having positive currenttransmitting means comprising, in combination, a trough-shaped contacttongue made of soft metal, and a tubular shell surrounding the softmetal trough-shaped tongue with a pressed fit thereon to produce apermanentlyjoined one-piece connector adapted to receive an electricalconductor thereinto, said soft metal tongue being adapted to lie inengagement with the conductor aforesaid, whereby a crimping forceapplied to the connector causes the soft metal tongue to cold-flow byinternal compression into intimately positive electrical engagement withthe conductor and also to act as the current transmitting means, whilethe tubular shell withstands said crimping force and maintains theinternal compression.

2. A solderless electrical-wire connector comprising, in combination, asoft metal contact member of sufficient length to receive and liealongside and in engagement with an electrical conductor, said contactmember being arcuate in cross-section of slightly more than and havingits longitudinal edges thinned down to feather-edge crescent shapeformation, and a tubular reinforcing shell surrounding the arcuatecontact member with a pressure fit thereon thus producing apermanently-joined one-piece connector assembly, the contact memberbeing seated longitudinally against the inner surface of said outershell, whereby a crimping groove depressed longitudinally into theconnector causes the soft metal contact member to coldfiow into grippingconnection with the conductor, with the thin edges of the contact membercrowding around and tightly packing against the conductor and beingmaintained under pressure from end to end thereof by said shell, therebyforming a positive and permanent electrical connection.

3. An electrical wire connector comprising, in combination, acylindrical member of uniform inside diameter, and a contact part ofarcuate cross section of slightly more than 180 pressed into thecylindrical member in seated engagement therewith to form a permanentassembly, thereby making a cylindrical connector of minimum-outsidediameter with an internal wire passage of maximum size adapted toreceiveand engage a maximum-size wire, and adapted to be crimped bywhich to cold-flow the contact part and the wire together in one compactmass within the cylindrical member engaging said wire.

GEORGE C. THOMAS, JR.

